This invention relates to a method of measuring residual stresses in the material of an object and, particularly, in an object having a curved surface accessible from one side only.
Those skilled in the art know a method of ultrasonic measurement of stresses in the material of an object under test from Polish patent publication No. 235,656. According to that method, beams of two types of ultrasonic waves are propagated in the material of the object parallel to a surface of the object. The travel times of pulses of these two types of ultrasonic subsurface waves over a known path in the material of the object under test and in a reference material are measured. Next, the absolute values of stresses in the material of the object under test are calculated from the differences of the travel times.
This known method of ultrasonic measurement of stresses and the equipment for implementation thereof enable the values of longitudinal components of residual stresses to be determined in the objects with plane surfaces. The described method is not applicable to objects with curved surfaces.